Oral Presentation 18th International Congress on Photobiology 2024

Visible light (VL, 400-700 nm) was previously reported to have no photobiologic effects on the skin. However, recent studies have demonstrated that it can induce relatively more intense and longer lasting pigmentation, compared to ultraviolet A1 (UVA1, 340-400 nm), in dark-skinned individuals (skin phototypes IV-VI).[1] Additionally, these effects of VL were shown to be potentiated by long wavelength UVA1 (370-400 nm).[2] Subsequent studies also demonstrated that the combination of VL and UVA1 (VL+UVA1, 370-700nm) was able to induce erythema in light-skinned individuals (skin phototypes I-III).[3] Although biologic effects of VL have been established, there is lack of standardized testing guidelines to evaluate photoprotective efficacy of products against this part of sunlight.  This invited presentation will discuss the evolution of knowledge of photobiologic effects of VL, associated phototesting methodologies, and available means of VL photoprotection. 

1. Mahmoud BH, Ruvolo E, Hexsel CL, Liu Y, Owen MR, Kollias N, et al. Impact of long-wavelength UVA and visible light on melanocompetent skin. J Invest Dermatol. 2010 Aug;130(8):2092-7.
2. Kohli I, Chaowattanapanit S, Mohammad TF, Nicholson CL, Fatima S, Jacobsen G, et al. Synergistic effects of long-wavelength ultraviolet A1 and visible light on pigmentation and erythema. Br J Dermatol. 2018 May;178(5):1173-80.
3. Kohli I, Zubair R, Lyons AB, Nahhas AF, Braunberger TL, Mokhtari M, et al. Impact of Long-Wavelength Ultraviolet A1 and Visible Light on Light-Skinned Individuals. Photochem Photobiol. 2019 Nov;95(6):1285-87.